Region limiting excavation control system for construction machine

Abstract

In an excavation area limiting control system for a construction machine for limitingly controlling an area to be excavated, a region where a front device 1A is movable is set beforehand. The position and posture of the front device are calculated based on signals from angle sensors 8a-8c, and a target speed vector of the front device is calculated based on detection signals from control lever units and load pressures detected by pressure sensors 270a to 271b. The target speed vector is modified so that a vector component of the target speed vector in the direction toward the boundary of the set region is reduced when the front device is within the set region near the boundary thereof, and the front device is returned to the set region when the front device is outside the set region. Control signals corresponding to the modified target speed vector are further modified depending on the load pressures and output to proportional solenoid valves 210a to 211b. As a result, the excavation within a limited area can be implemented efficiently and smoothly, and stable control is achieved with good accuracy regardless of change in the load pressures of hydraulic actuators.

We claim: 
     
       1. An excavation area limiting control system for limitingly controlling an area to be excavated in a construction machine, comprising a plurality of driven members (1a-1f) including a plurality of front members (1a-1c) which make up a multi-articulated type front device (1A) and are vertically rotatable, a plurality of hydraulic actuators (3a-3f) for respectively driving said plurality of driven members, a plurality of manipulation means (204a-204f; 4a-4f) for instructing operation of said plurality of driven members, and a plurality of hydraulic control valves (5a-5f) driven in accordance with control signals from said plurality of manipulation means for controlling flow rates of a hydraulic fluid supplied to said plurality of hydraulic actuators, wherein said system further comprises: (a) area setting means (7, 9a) for setting an area to be excavated by said front device (1A);   (b) first detecting means (8a-8d) for detecting status variables with regard to the position and posture of said front device;   (c) second detecting means (270a-271b; 270a) for detecting load pressures of particular front actuators (3a, 3b; 3a) of said plurality of hydraulic actuators (3a-3f) which are associated with at least one or more particular front members (1a, 1b; 1a);   (d) first calculating means (9b) for calculating the position and posture of said front device based on signals from said first detecting means;   (e) signal modifying means (209c, 9d-9i, 209j, 9k, 210a-211b; 10a-11b; 12) for, based on the control signals from the manipulation means (204a, 204b; 4a, 4b) of said plurality of manipulation means which are associated with said front device and the values calculated by said first calculating means, carrying out calculation of a target speed vector (Vca) of said front device and modifying the control signals from the manipulation means (204a, 204b; 4a, 4b) associated with said front device so that, when said front device is within said set area to be excavated and near the boundary of said set area, said front device is allowed to move in the direction along the boundary of said set area to be excavated and a moving speed of said front device in the direction toward the boundary of said set area to be excavated is reduced, and further said front device is allowed to move in the direction along the boundary of said set area to be excavated even when the front device reaches said boundary of the set area; and   (f) output modifying means (209j, 209Cj) for, based on signals from said second detecting means (270a-271b; 270a), further modifying, of the control signals modified by said signal modifying means, the control signals from the manipulation means (204a, 204b; 4a, 4b; 204a; 4a) which are associated with said particular front members (1a, 1b; 1a) so that said front device is moved as per said target speed vector (Vca) regardless of change in the load pressures of said particular front actuators (3a, 3b; 3a).   
     
     
       2. An excavation area limiting control system for a construction machine according to claim 1, wherein said signal modifying means comprises second calculating means (209c, 9d) for calculating an input target speed vector (Vc) of said front device based on the control signals from the manipulation means (204a-204c; 4a-4c) associated with said front device (1A), third calculating means (9e) for modifying said input target speed vector (Vc) so that a vector component of said input target speed vector (Vc) in the direction toward the boundary of said set area is reduced, and valve control means (9f, 209j, 9k, 210a-211b; 10a-11b, 12) for driving the associated hydraulic control valves (5a, 5b) so that said front device is moved in accordance with the target speed vector (Vca) modified by said third calculating means, and wherein said output modifying means is constituted as part (209j ) of said valve control means. 
     
     
       3. An excavation area limiting control system for a construction machine according to claim 1, wherein said signal modifying means carries out, based on the control signals from those ones (204a-204c; 4a-4c) of said plurality of manipulation means which are associated with said front device (1A) and the values calculated by said first calculating means, calculation of a target speed vector (Vca) of said front device, modifies the control signals from the manipulation means associated with said front device so that, when said front device is within said set area near the boundary of said set area, said front device is allowed to move in the direction along the boundary of said set area and a moving speed of said front device in the direction toward the boundary of said set area is reduced, and modifies the control signals from the manipulation means (204a, 204b; 4a, 4b) associated with said front device so that, when said front device is outside said set area, said front device is returned to said set area, and wherein said output modifying means (209j ; 209Cj) further modifies, based on signals from said second detecting means (270a-271b; 270a), the control signals from the manipulation means (204a, 204b; 4a, 4b; 204a; 4a) which are associated with said particular front members (1a, 1b; 1a) for any case of modification of the control signals so that said front device is moved as per said target speed vector (Vca) regardless of change in the load pressures of said particular front actuators (3a, 3b; 3a). 
     
     
       4. An excavation area limiting control system for a construction machine according to claim 3, wherein said signal modifying means includes second calculating means (209c, 9d) for calculating an input target speed vector (Vc) of said front device based on the control signals from the manipulation means (204a-204c; 4a--4c) associated with said front device (1A), third calculating means (9e, 9g) for modifying said input target speed vector (Vc) so that, when said front device is within said set area near the boundary of said set area, a vector component of said input target speed vector in the direction toward the boundary of said set area is reduced, and modifying said input target speed vector (Vc) so that, when said front device is outside said set area, said front device is returned to said set area, and valve control means (9f, 9h, 9i, 209j, 9k, 210a-211b; 10a-11b, 12) for driving the associated hydraulic control valves so that said front device is moved in accordance with the target speed vector (Vca) modified by said third calculating means, and wherein said output modifying means is constituted as part (209j ) of said valve control means. 
     
     
       5. An excavation area limiting control system for a construction machine according to claim 2, wherein said valve control means includes fourth calculating means (9f, 209j ; 9f, 9h, 9i, 209j ) for calculating target operation command values for said associated hydraulic control valves (5a, 5b) based on the target speed vector (Vca) modified by said third calculating means (9e; 9e. 9g), and output means (9k, 210-211b; 10a-10b, 12) for producing control signals for said associated hydraulic control valves (5a, 5b) based on the target operation command values calculated by said fourth calculating means, and wherein said output modifying means is constituted as part (209j ) of said fourth calculating means and, in the calculation of said target operation command values, modifies those ones of said target operation command values which are associated with said particular front actuators (3a, 3b; 3a), depending on the load pressures detected by said second detecting means (270a-271b; 270a). 
     
     
       6. An excavation area limiting control system for a construction machine according to claim 5, wherein said fourth calculating means includes target actuator speed calculating means (9f, 9h ) for calculating target actuator speeds from the target speed vector (Vca) modified by said third calculating means (9e; 9e, 9g), and target operation command value calculating means (209j ) for calculating the target operation command values for said associated hydraulic control valves (5a, 5b) from said target actuator speeds and the load pressures detected by said second detecting means (270a-271b; 270a) in accordance with preset characteristics. 
     
     
       7. An excavation area limiting control system for a construction machine according to claim 1, wherein said signal modifying means includes second calculating means (209c, 9d) for calculating an input target speed vector (Vc) of said front attachment based on the control signals from the manipulation means (204a, 204b; 4a, 4b) associated with said front attachment (1A), and third calculating means (9e) for modifying said input target speed vector (Vc) so that a vector component of said input target speed vector in the direction toward the boundary of said set area is reduced and said system further comprises input modifying means (209c) for, based on the signals from said second detecting means (270a-271b; 270a), modifying the input target speed vector (Vc) calculated by said second calculating means so that the speed vector corresponding to the control signals from said manipulation means is obtained regardless of change in the load pressures of said particular front actuators (3a, 3b; 3a). 
     
     
       8. An excavation area limiting control system for a construction machine according to claim 7, wherein said second calculating means includes fifth calculating means (209c) for calculating input target actuator speeds based on the control signals from the manipulation means (204a, 204b; 4a, 4b) associated with said front device (1A), and sixth calculating means for calculating the input target speed vector (Vc) of said front device from the input target actuator speeds calculated by said fifth calculating means, and wherein said input modifying means is constituted as part (209c) of said fifth calculating means and, in the calculation of said input target actuator speeds, modifies the input target actuator speeds of said particular front actuators (3a, 3b; 3a) depending on the load pressures detected by said second detecting means (270a-271b; 270a). 
     
     
       9. An excavation area limiting control system for a construction machine according to claim 8, wherein said fifth calculating means calculates said input target actuator speeds from the control signals from the manipulation means (204a, 204b; 4a, 4b) associated with said front device (1A) and the load pressures detected by the second detecting means (270a-271b; 270a) in accordance with the preset characteristics. 
     
     
       10. An excavation area limiting control system for a construction machine according to claim 6, wherein said preset characteristics are determined based on flow rate load characteristics of the hydraulic control valves (5a, 5b; 5a) associated with said particular front actuators (3a, 3b; 3a). 
     
     
       11. An excavation area limiting control system for a construction machine according to claim 2, said plurality of manipulation means being manipulation means (204a-204f) of an electric lever type generating electric signals as said control signals, wherein: said valve control means includes electric signal generating means (9f, 209j, 9k; 9f, 9h, 9I, 209j, 9k) for calculating target operation command values for said associated hydraulic control valves (5a, 5b) based on the target speed vector (Vca) modified by said third calculating means (9e; 9e, 9g) and outputting electric signals corresponding to the calculated target operation command values, and electro-hydraulic converting means (210-211b) for converting said electric signals into hydraulic signals and outputting said hydraulic signals to said associated hydraulic control valves (5a, 5b), and wherein said output modifying means is constituted as part (209c) of said electric signal generating means and, in the calculation of said target operation command values, modifies those ones of said target operation command values which are associated with said particular front actuators (3a, 3b; 3a), depending on the load pressures detected by said second detecting means (270a-271b; 270a).   
     
     
       12. An excavation area limiting control system for a construction machine according to claim 2, said plurality of manipulation means (4a-4f) being of a hydraulic pilot type generating pilot pressures as said control signals, the associated hydraulic control valves (5a-5f) being driven by a manipulation system including said manipulation means of a hydraulic pilot type, wherein: said valve control means includes electric signal generating means (9f, 209j, 9k; 9f, 9h, 9i, 209j, 9k) for calculating target operation command values for said associated hydraulic control valves (5a, 5b) based on the target speed vector (Vca) modified by said third calculating means (9e; 9e, 9g) and outputting electric signals corresponding to the calculated target operation command values, and pilot pressure modifying means (10a-11b, 12) for outputting, in accordance with said electric signals, pilot pressures which are to be substituted for the pilot pressures from said manipulation means, and wherein said output modifying means is constituted as part (209j ) of said electric signal generating means and, in the calculation of said target operation command values, modifies those ones of said target operation command values which are associated said particular front actuators (3a, 3b; 3a), depending on the load pressures detected by said second detecting means (270a-271b; 270a).   
     
     
       13. An excavation area limiting control system for a construction machine according to claim 12, wherein said manipulation system includes a first pilot line (44a) for introducing a pilot pressure to the corresponding hydraulic control valve (5a) so that said front device (1A) is moved away from said set area, and wherein said pilot pressure modifying means includes electro-hydraulic converting means (10a) for converting said electric signal into a hydraulic signal and higher pressure selecting means (12) for selecting a higher one of the pilot pressure in said first pilot line and the hydraulic signal output from said electro-hydraulic converting means, and introducing the selected pressure to said corresponding hydraulic control valve. 
     
     
       14. An excavation area limiting control system for a construction machine according to claim 13, wherein said manipulation system includes second pilot lines (44b/45a/45b) for introducing pilot pressures to the corresponding hydraulic control valves (5a/5b) so that said front device (1A) is moved toward said set area, and wherein said pilot pressure modifying means includes pressure reducing means (10b/11a/11b) disposed in said second pilot lines for reducing the pilot pressures in said second pilot lines in accordance with said electric signals. 
     
     
       15. An excavation area limiting control system for a construction machine according to claim 2, wherein said third calculating means (9e) maintains said input target speed vector (Vc) as it is when said front attachment (1A) is within said set area but not near the boundary of said set area. 
     
     
       16. An excavation area limiting control system for a construction machine according to claim 2, wherein the vector component of said input target speed vector (Vc) in the direction toward the boundary of said set area is a vector component vertical to the boundary of said set area. 
     
     
       17. An excavation area limiting control system for a construction machine according to claim 2, wherein said third calculating means (9e) reduces the vector component of said input target speed vector (Vc) in the direction toward the boundary of said set area such that an amount of reduction in said vector component is increased as a distance between said front device (1A) and the boundary of said set area decreases. 
     
     
       18. An excavation area limiting control system for a construction machine according to claim 4, wherein said third calculating means (9g) modifies said input target speed vector (Vc) so that said front device (1A) is returned to said set area, by changing a vector component of said input target speed vector (Vc) in the direction vertical to the boundary of said set area into a vector component in the direction toward the boundary of said set area. 
     
     
       19. An excavation area limiting control system for a construction machine according to claim 4, wherein said third calculating means (9g) reduces the vector component in the direction toward the boundary of said set area as a distance between said front device (1A) and the boundary of said set area decreases. 
     
     
       20. An excavation area limiting control system for a construction machine according to claim 1, wherein said front device (1A) includes a boom (1a) and an arm 1(b) of a hydraulic excavator. 
     
     
       21. An excavation area limiting control system for a construction machine according to claim 20, wherein said particular front actuators include at least a boom cylinder (3a) for driving said boom (1a), and said second detecting means include at least means (270a) for detecting a load pressure in the boom-up direction.